The rapid digitalization of the world has affected engineering and design in a variety of ways, including the introduction of new computer-aided ideation tools. Cognitive assistants (CA), an increasingly common digital technology, use natural-language processing and artificial intelligence to provide computational support. Because CAs are capable of emulating humans in some tasks, they may be suited to support ideation activities when trained coaches or facilitators are not available. However, the effects and perception of CA-facilitated ideation are not fully understood. This study compared co-located brainstorming groups facilitated by human facilitators and a CA facilitator. We found that human facilitation was associated with the blocks/interruptions state because they used these moments to initiate facilitation; conversely, cognitive assistant facilitation was associated with the deviations and silence state. Human facilitation was also found to produce a more equal distribution of speaking time. Finally, post-task interviews showed that participants became frustrated due to the lack of affordances to indicate the status and functionality of the device.